Treadle vac conversion to newer master cylinder?

[Resurrector]

Hi, I am giving up on the TreadleVac master cylinder I rebuilt, it pressures up somehow and causes the left front brake to stay on. I discovered if you reach into the master cyl with a screwdriver and push down on that valve sticking up, it releases the pressure. Has anyone ran intothis?

Now thinking I'll convert it to a newer, possibly dual master cyl...something normal. Does anyone know what master will fit on with the same bore diameter and fitting size for the brake line?

[58limited]

I don't know how easy a conversion will be. I've been told by two different '58 Buick experts to send your master cylinder/power booster off to be rebuilt. They never had luck rebuilding them themselves.